Histology of

Male Reproductive System

1

Dr. Rajesh Ranjan

Assistant Professor

Deptt. of Veterinary Anatomy

C.V.Sc, Rewa

Male Reproductive System

A-Testis

B-Epididymis

C-Ductus Deferens

D-Urethra

1-Pelvic part

2-Penile part

E-Penis

G-Accessory Glands

1. Seminal vesicles

2-Prostate gland

3-Bulbouretheral gland/ Cowper’s gland

Testis The testis remains covered by:

Tunica vaginalis-

The outermost covering (peritoneal covering of thetestis and epididymis).

It has a parietal and visceral layer. The parietal layerremains adhered to the scrotum while the viscerallayer adheres to the capsule of the testis. The spacebetween the these two layers is called the vaginalcavity.

The layers consists of mesothelium lining andconnective tissue that blends with the underlyingconnective tissue of the scrotum.

Tunica albuginea: Capsule of the testis

Consists of dense irregular connective tissue, predominantlycollagen fibers, few elastic fibers and myofibroblast.

It has vascular layer (Tunica vasculosa) that containsanatomizing branches of testicular artery and veins.

The tunica albuginea gives connective tissue trabeculae calledseptula testis which converge towards the mediastinumtestis.

The septula testis divides the testicular parenchyma intonumber of testicular lobules. Each lobule contains 1-4seminiferous tubules.

Mediastinum testis is a connective tissue area containingthe channels of rete testis, large blood and lymph vessels. Inbull it occupies the central position along the longitudinalaxis of the gonad.

Interstitial cells (Leydig cells)The inter-tubular spaces of the testis contain loose C.T., blood and lymph

vessels, fibrocytes, free mononuclear cells and interstitial cells called

Leydig cells.

These Leydig cells are

▪Endocrine cells.

▪Have acidophilic cytoplasm.

▪Polyhedral in shape; has 1 or 2 spherical nuclei.

▪Form cords or clusters.

▪1% ram, 5% bulls, 20-30% in boars.

▪Produce testicular androgens (Testosterone)

▪In Boars they produce large amount of estrogen.

Seminiferous tubules:▪Comprises of convoluted (tubuli contorti) and straight

tubule (tubuli recti).

▪Convoluted Seminiferous tubules are tortuous two-ended

loops.

▪Lined by stratified spermatogenic/ germinal epithelium.

▪Underlined by basal lamina.

▪Beneath the basal membrane lies the lamina propria.

▪The spermatogenic epithelium contains

▪Spermatogenic cells

▪Sertoli cells/ Sustentacular cells.

Cross section showing one Seminiferous tubule

Spermatogenic cells: It is arranged as complex stratified epithelium which consists of

stem cells (spermatogonia) at the base of the epithelium.

The other cells are arranged in the order of development i.e.,spermatogonia, primary spermatocytes, secondary spermatocytes,spermatids and spermatozoa.

The process of differentiation of spermatogonia to spermatozoa iscalled spermatogenesis.

Spermatogonia are immature spermatogenic cells lying on thebasement membrane of Seminiferous tubule.

They undergo mitosis to differentiate intoType-A andType-B cells.

The type-A spermatogonia serves as stem cell of germinal epithelium.

The type-B spermatogonia undergo maturation to form the primaryspermatocytes.

Primary spermatocyte:

These are the largest germ cells occupying the middle region of

Seminiferous tubule.

They have large rounded nucleus with coarse chromatin

clumps.

The primary spermatocytes undergo first meiotic division to

form the secondary spermatocytes with haploid number of

chromosomes.

Secondary spermatocyte:

These are short lived cells and intermediate in size between the

primary spermatocytes and spermatids.

Their nuclei have less dense chromatin and undergo second

meiotic division to form the spermatids.

Spermatids:

They are much smaller and lie in groups along the margins

of sertoli cells.

With the formation of spermatids the first phase of

spermatogenesis i.e., spermatocytogenesis is completed.

The second phase (Spermiogenesis) starts where the non-

motile spermatids converts into motile spermatozoa.

Sustantacular cell (Sertoli cell ):• Irregularly outlined tall columnar cells rest on basallamina.

• Have oval or pear-shaped nuclei and located in thebroad basal portion of the cell and contains largenucleoli.

• Form hemidesmosomes with the basal lamina.

• Looses its mitotic activity during puberty.

• A cross section of somniferous tubule has about 20evenly spaced sustantacular cells.

• Adjacent sertoli cells have lateral tight junctions.

• This form a basal and an apical compartment formingblood-testis barrier.

Sertoli cells

Basement membrane:

Present beneath the epithelium and contains club shaped

projections that extend into the basal infoldings of sustentacular

cells and spermatogonia.

Lamina propria:

Made up of collagen and elastic fibers, fibroblasts, lymphocytes and

monocytes. These lymphocytes and monocytes never invade the

tubular epithelium.

It also contains 1-5 layers of peritubular cells just beneath the

basement membrane that contains actin filament bundles and are

capable of contraction.

Tubuli recti:

Lining epithelium varies from simple cuboidal (proximal part) to

simple columnar (distal part) in bull.

Rete Testis:

• It is irregular anastomsing channel surrounded by vascular

connective tissue of the mediastinum,

• Lined by simple cuboidal to columnar epithelium, some have

microvilli.

• Elastic fibers and contractile cells are present beneath the

epithelium.

Ductuli efferenti:

The rete testis is connected to the ductus eipdidymis by 8-25

ductuli efferenti.

They are gathered in small lobules and lined by patches of

nonciliated cuboidal cells alternate with ciliated columnar cells.

Houses lymphocytes in their basal area.

1. Ductuli efferenti

Ductus Epididymis:

Divided into a head, body & tail.

Surrounded by loose connective tissue covered by the visceral

layer of tunica vaginalis.

Long & tortuous.

Lined by pseudo stratified columnar epithelium with

stereocilia.

The epithelial height as well as the length of stereocilia

decreases from head to tail region.

The smooth muscle thickness increases from head to tail region.

The epithelium contains some specific cell types like polygonal

basal cells and principal cells.

Ductus Deferens: From the epididymis the ductus deferens, a straight tube with a

thick muscular wall, continues towards the prostatic urethra

and empties into it.

It is characterized by a narrow lumen and a mucosa with

longitudinal folds, covered along most of its extent by pseudo

stratified columnar epithelium with stereocilia.

The lamina propria is rich in elastic fibers and the thick

tunica muscularis consists of longitudinal inner and outer

layers separated by a circular layer. The abundant smooth

muscle produces strong peristaltic contractions that participate

in the expulsion of the spermatozoa during ejaculation.

Urethra: The histological details include the basic four layers:

Tunica mucosa: The epithelium is transitional butchanges to stratified squamous at the external urethralorifice.

Tunica submucosa: It is a connective tissue layer and hascavernous spaces that are typical of erectile tissue.

Tunica muscularis: It has inner and outer longitudinaland a middle circular layer of smooth muscles as in bladderbut towards the external urethral orifice, it acquires anexternal layer of skeletal muscle called Urethralismuscle.

Tunica serosa/ adventitia: is a fibrous layer.

Penis: The main component of the penis are the erectile tissues and

the urethra, surrounded by tunica albuginea and skin.

The erectile tissues are corpus cavernosum penis placed

dorsally and corpus cavernosum urethrae (corpus

spongiosum) located ventrally and surrounds the urethra.

At its end it dilates, forming the glans penis.

Trabeculae arise from the tunica albuginea and enters the

erectile tissues.

Accessory sex glands:Seminal vesicle:

Compound tubular/ tubulo-alveolar gland.

Glandular epithelium is pseudo stratified columnar with few

spherical basal cells.

The intralobular and main excretory duct is lined by simple

cuboidal epithelium in bull and stratified columnar in equines.

Lamina propria is highly vascularised loose connective tissue

which gives trabeculae that divides the glands into number of

lobules.

Tunica muscularis and adventitia is also present.

Prostate gland:

Histologically prostate consists of parenchyma (tubulo-alveolarglands) and a characteristic fibro muscular stroma.

The glandular parenchyma is formed by irregular prostaticalveoli with wide lumen.

Secretory lining of alveoli varies from cuboidal to columnardepending upon activity.

The lumen contains spherical prostatic concretions or corporaamylacea which are formed by condensation of prostaticsecretions.

The fibro muscular stroma supports the parenchyma and ismade of smooth muscle fibers mixed with connective tissuefibers running in different directions.

The fibro elastic capsule surrounding the prostate is rich insmooth muscle. Septa from this capsule penetrate the gland anddivide it into lobes.

Bulbourethral gland:

Compound tubulo-alveolar gland in bull, stallion and ram,

compound tubular gland in boar, cat and bucks and absent in

dogs.

Glandular epithelium is simple columnar with occasional basal

cells.

The collecting duct has simple cuboidal to columnar

epithelium.

The intraglandular duct has pseudostratified columnar

epithelium.

The bulbourethral duct is lined by transitional epithelium.

The gland is covered by fibro elastic capsule containing

striated muscle.

Assignment:

A well labelled histological representation of male

reproductive system with key histological differences

among species in practical note book.

Thanks!